The present invention relates generally to diagnostic imaging and, more particularly, to a method and apparatus of scoring an arterial obstruction.
Typically, in computed tomography (CT) imaging systems, an x-ray source emits a fan-shaped beam toward a subject or object, such as a patient or a piece of luggage. Hereinafter, the terms “subject” and “object” may be interchangeably used and shall include anything capable of being imaged. The beam, after being attenuated by the subject, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is typically dependent upon the attenuation of the x-ray beam by the subject. Each detector element of the detector array produces a separate electrical signal indicative of the attenuated beam received by each detector element. The electrical signals are transmitted to a data processing system for analysis which ultimately produces an image.
Generally, the x-ray source and the detector array are rotated about the gantry within an imaging plane and around the subject. X-ray sources typically include x-ray tubes, which emit the x-ray beam at a focal point. X-ray detectors typically include a collimator for collimating x-ray beams received at the detector, a scintillator for converting x-rays to light energy adjacent the collimator, and photodiodes for receiving the light energy from the adjacent scintillator and producing electrical signals therefrom.
Typically, each scintillator of a scintillator array converts x-rays to light energy. Each scintillator discharges light energy to a photodiode adjacent thereto. Each photodiode detects the light energy and generates a corresponding electrical signal. The outputs of the photodiodes are then transmitted to the data processing system for image reconstruction.
Specifically, cardiac CT is particularly useful in assisting medical providers in assessing a patient's risk of cardiovascular disease, including heart attack, heart failure, and stroke. One particular implementation of cardiac CT is the detection of calcium deposits in the coronary arteries of medical patients. The presence of calcium is indicative of atherosclerosis, or hardening of the arteries. Assessing the calcification in coronary arteries is commonly referred to as coronary artery calcium scoring (CACS). While detection of calcium deposits in the arteries is helpful in determining a patient's risk of heart disease, other factors must be considered in conjunction with a calcification score including age, gender, cholesterol levels, history of heart disease, diabetes, high blood pressure, weight, physical inactivity, and cigarette smoking. No single test or examination can provide a complete and accurate profile of a patient's risk of cardiovascular disease, but determining a coronary artery calcification score does assist medical providers in determining a personalized assessment of a patient's risk of heart attack, heart failure, and/or stroke.
According to statistics released by Northwestern Memorial Hospital, every thirty-three seconds someone in the United States dies from cardiovascular disease. Cardiovascular disease, including heart attack, heart failure, and stroke continues to be the leading cause of death for men and women in America. Therefore, there is increasingly a need to accurately detect and assess calcium deposits in the patient's coronary arteries so as to minimize the risk of atherosclerosis with medicine, diet, and exercise. Current calcification scoring techniques are susceptible or greatly affected by limited image resolution such as in-plane image blurring and axial partial volume effect. As a result, the weight of the detected calcium region is estimated rather than accurately determined. Further, when determining the volume of these calcification regions, the estimated volumes are typically higher than the true volume of the calcium region thereby leading to inappropriate treatment plans.
Therefore, it would be desirable to design an apparatus and method of calcification scoring an arterial obstruction of a subject that more accurately reflects a true weight and/or volume of the arterial obstruction that is not greatly affected by limited image resolution.